The use of surgically implanted mechanical heart valves has become widespread and even routine. One type of mechanical heart valve in common use is described in U.S. Pat. No. 4,276,658 and is depicted in FIG. 1 which shows a valve 2a comprising an orifice ring 4a positioned within an implanting flange, or sewing ring 6a. An occluder, in the form of one or two leaflets 7a, is pivotally supported by a pivot mechanism (not shown) within the orifice ring 4a to alternately open and close a blood flow passageway through a passageway 5a of the orifice ring having an interior surface 11a. The occluder acts as a check valve to prevent regurgitation of blood through the orifice ring 4a when pumping action of the heart produces localized back pressure. The orifice ring 4a is formed with upstanding projections 9a having flat inside surface sections 10a on which are located part of the pivot mechanism. The flat surface sections 10a form part of the otherwise curvilinear surface 11a.
Specialized tools have been developed to assist in the implantation of mechanical heart valves of the type described in the '658 patent. An effective tool should be capable of both holding the valve and allowing it to be manipulated at the implantation site in order to properly position it. The tool should also provide easy engagement with and disengagement from the valve without damaging the leaflets and/or dislodging them from the pivot mechanism.
FIG. 1 also illustrates an example of a tool for holding the type of valve described above which includes a body 12 and a jaw 14 linked by flexible hinges 16 (only one is shown). Flanges 18 and 20 on the body 12, and flanges 22 and 24 on a jaw 14 form arcuate channels 19 and 23, respectfully, which are inserted through the passageway 5a of the orifice ring 4a to abut the inner circumferential surface 11a so as to engage the valve. A filament 26, when tied tightly around the body 12 and jaw 14, holds the jaw and body extended so that the valve is securely engaged within the arcuate channels. Cutout surfaces, or reliefs 28 and 30 in the body 12 and jaw 14, respectively, provide clearance to fit about the projections 9a. When the filament 26 is cut, the body 12 and jaw 14, only linked by flexible hinges 16, may be manipulated to disengage the arcuate channels 19 and 23 from orifice ring 4a, thereby allowing the tool to be separated and retracted from the valve.
A potential disadvantage of this type of tool is that after the filament 26 is cut, the body 12 and/or jaw 14 may flail about and pinch a sealing surface of the valve or even cause an occluder to become dislodged from the pivot mechanism.
For convenience, valve prostheses and their associated holders are commonly assembled by the manufacturer and shipped as assemblies in sterile enclosures. To prevent damage to the valve during shipping and handling, the assembly must form a stable structure.
Therefore, there is a need for a tool for securely holding a heart valve prosthesis and rotating it within the surrounding sewing ring which may easily be selectively separated from the valve. A need also exists for a tool that can be released and withdrawn from the valve without damaging it. Such a tool should also be capable of adequately supporting the valve in order to prevent it from being damaged during shipment.